Deep Understanding of Heterogeneous Catalysis and Industrial Catalytic Processes
(EPRI, AIST)
Ammonia Synthesis
Impact of Graphitization of Cs-promoted Ru/C. Carbon-supported ruthenium catalysts facilitate electrically-assisted Haber–Bosch ammonia synthesis. However, the relationship between carbon supports and catalytic performance remains ambiguous. In this study, we developed ordered mesoporous carbon plates (MCPs) with varying graphitization degrees as Cs-promoted Ru catalyst supports, examining correlations between ammonia synthesis rate and key structural parameters, included graphitization degree, Ru nanoparticle size, and Cs/Ru ratio.
A Rubost Catalyst: Cs-promoted Ru/gamma-Al2O3. The development of efficient and stable Ru catalysts with favorable textural properties is crucial for synthesis of decarbonized NH3, a potential hydrogen carrier in a future hydrogen economy. We demonstrated that Cs-promoted Ru/γ-Al2O3 catalysts are highly active and stable in ammonia synthesis under intermittent operation conditions.
Boosting the active sites of a Cs-Ru/SGCNT catalyst for ammonia synthesis. For the decarbonization of ammonia industry, a super-growth carbon nanotube (SGCNT)-supported, Cs-promoted Ru catalyst (Cs-Ru) was developed for mild ammonia synthesis (≤400 °C and ≤8 MPaG), particularly under intermittent operation conditions. It produced ≈ 15 vol% of ammonia (rate ≈ 35 mmol g−1 h−1) at 380–400 °C and 5 MPaG (an H2/N2 molar ratio of 3 and a GHSV of 7000 h−1) that was close to thermodynamic equilibrium.
DFT calculations to understand N2 activation on B5 site of Ru/MgO(111). N2 dissociative adsorption is commonly the rate-determining step in thermal ammonia synthesis. Herein, we performed density functional theory (DFT) calculations to understand the N2 dissociation mechanism on models of unsupported Ru(0001) terraces, Ru B5 sites, and polar MgO(111)-supported Ru8 cluster mimicking a B5 site geometry, denoted (Ru8(B5-like)/MgO(111)).
Cs-promoted Ru/@SBA-15 Composite Material Works. An active and durable Ru-based catalyst using an inert support such as SBA-15 for mild ammonia synthesis can be prepared, where the Cs-promoted Ru active sites are delicately built in the nanospace.
Sustainable Energy Fuels,2020, 4, 5802-5811.
https://doi.org/10.1039/D0SE01077D
Sustainable Energy Fuels 2020, 4, 832-842
New Organic Synthesis via Photo-electrochemical and Chemical Lntegrated Process
We developed a NaBr-assisted photoelectrochemical and photochemical integrated process for the complete isomerization of dimethyl maleate to dimethyl fumarate under solar-simulated light irradiation. This process also produced bulky fumarate ester derivatives at high yields (85–100%). This newly developed process is an innovative and environmentally friendly strategy that goes beyond the conventional thermochemical process to achieve the precise synthesis of fumarate derivatives under mild conditions.
ACS Sustainable Chemistry & Engineering 2021, 9(19), 6886-6893.
(Dr. H. Tateno)
https://pubs.acs.org/doi/abs/10.1021/acssuschemeng.1c01871
The conversion of glycerol, a major byproduct of the biodiesel industry, into value-added chemicals is a topic of significant academic and industrial importance because it can potentially decrease production costs and waste amounts. This process may become even greener if the conversion of glycerol is driven by renewable energy in ambient temperature instead of conventional thermochemical reactions. Herein, we have developed an energy-efficient method for the photoelectrochemical oxidation of glycerol to dihydroxyacetone (DHA), a high-value-added chemical, over a Ta-doped BiVO4/WO3/F-doped tin oxide (FTO) (Ta:BiVO4) photoanode with higher acid resistance than a conventional non-doped BiVO4/WO3/FTO photoanode (BiVO4). The DHA selectivity of the Ta:BiVO4 anode was close to 100%, and the amounts of undesirable products, such as glyceraldehyde and formic acid, were negligible.
ACS Sustainable Chemistry & Engineering 2022, 10(23) 7586-7594.
(Dr. H. Tateno)
https://doi.org/10.1021/acssuschemeng.2c01282
Biomass Conversion to High Value-added Products
Bifunctional SBA-15 as Solid Acid.
Lignocellulosic biomass is a promising renewable resource that can be converted into glucose, a precursor for the synthesis of high-value bio-chemicals, such as 5-hydroxymethylfurfural (HMF). However, the conversion of glucose to HMF using conventional liquid and solid acids is challenging due to the formation of byproducts, leading to low HMF yield. In this study, bifunctional solid acid catalysts (named Al-SA-S15) consisting of aluminum (Al) as Lewis acid sites and sulfonic acid (SA) as Brønsted acid sites were prepared by direct synthesis.
Materials Today Sustainability 2023, 24, 100470.
Integrated CO2 Capture and Reduction to CH4
Alkali- and Alkaline-promoted Ni/γ-Al2O3 Catalysts Can Do More. A desirable process for realizing a low-carbon society is the direct conversion of dilute CO2 from flue gases or air into highly concentrated hydrocarbons without a need for separate CO2 capture and purification processes. This approach in combination with the efficient catalyst shows encouraging potential for CO2 utilization, enabling direct air capture-conversion to value-added chemic
ACS Sustainable Chem. Eng. 2021, 9, 9, 3452–3463
(Dr. F. KOSAKA and Dr. K. Kuramoto)
Integrated CO2 capture and conversion (ICCC) using dual-function materials (DFMs) is one of the key technologies for addressing critical global environmental and energy issues. DFMs generally consist of alkali or alkaline earth metals for CO2 capture and transition metal catalysts for CO2 conversion. In this study, we studied the ICCC to CO using transition-metal-free DFMs to demonstrate their potential to directly produce syngas from atmospheric-level CO2.
Journal of CO2 Utilization, in press.
(Dr. Sasayama, Dr. Kosaka, Dr. Kuramoto)
https://doi.org/10.1016/j.jcou.2022.102049
Catalyst Characterization
X-ray Absorption Spectroscopy for Characterization of Solid Catalysts. The structural characters of Ba- and Cs-promoted Ru catalysts supported on a mesoporous carbon material (denoted as Ba-Ru/MPC and Cs-Ru/MPC) were examined by X-ray absorption spectroscopy and several characterization techniques, and correlated to their activities in long-term ammonia synthesis under intermittently varied conditions. The Ba-Ru/MPC contains barium species adhered to the surfaces of the Ru nanoparticles, creating more catalytically active sites for the dissociation of nitrogen molecules. By contrast, the Cs-Ru/MPC contains cesium hydroxides homogeneously covered on the MPC and Ru interfaces, enhancing the electronic property of the Ru nanoparticles and consequently facilitating ammonia synthesis.
Sustainable Energy Fuels 2020, 4, 832-842
Biodiesel Production
Ti-SBA-15 is a Weak Lewis Solid Acid. Carbonaceous Ti-SBA-15 materials with enhanced activity and durability (the leaching of silica was minimized) had been successfully synthesized by the self-assembly process and carbonization, and then applied as Lewis solid acid catalysts for transesterification of Jatropha oil with methanol into high-quality Jatropha BDF in both batch-type and fixed-bed reaction systems. Thorough characterizations confirmed that the catalytically active sites were related to the tetrahedrally coordinated Ti species with weakly Lewis acid property firmly incorporated on the carbonaceous SBA-15 framework.
Applied Catalysis B: Environmental 2016, 181, 800-809.
https://doi.org/10.1016/j.apcatb.2015.08.053
Applied Catalysis B: Environmental 2014, 148–149, 344-356.
https://doi.org/10.1016/j.apcatb.2013.11.009
Biodiesel Upgrading
(H-FAME)
Pd/SBA-15 is a Highly Active Hydrotreating Catalyst. The B20 fuels formulated by blending petro-diesel with the palm H-FAME with enhanced oxidation stability produced almost no sludges, suggesting that the palm H-FAME synthesized by partial hydrogenation of commercial palm BDF over supported Pd catalysts could be a reliable BDF source with high safety and security for use in high-blend fuels.
Applied Catalysis A: General 2020, 602, 117707
https://doi.org/10.1016/j.apcata.2020.117707
Catalysis Today 2019, 332, 122-131
https://doi.org/10.1016/j.cattod.2018.05.039
Comptes Rendus Chimie 2016, 19(10), 1166-1173
https://doi.org/10.1016/j.crci.2015.12.005
Bio-Oil Upgrading
CoMoSx and NiMoSx Sulfide Catalysts are Robust in HDS/HDO/HDN Reactions. A stepwise strategy was developed for direct upgrading of unconventional Jatropha bio-oil with high concentrations of heteroatoms, nitrogen especially, over sulfide catalysts to produce clean and drop-in biofuels.
Catalysts 2019, 9(5), 392
https://doi.org/10.3390/catal9050392
Catalysts 2018, 8(2), 59
https://doi.org/10.3390/catal8020059
Applied Catalysis B: Environmental 2014, 146, 237-243
https://doi.org/10.1016/j.apcatb.2013.05.040
Applied Catalysis A: General 2013, 456, 174-181
Mesoporous Materials
Molecular Scale Understanding of Self-assembling Process, Functionalization and Fine Chemical Synthesis:
A novel route for preparing highly ordered platelet SBA-15 materials with short mesochannels (ca. 200 nm) and large pore diameters up to 12 nm is reported for the first time. Appropriate quantities of Zr(IV) ions and trimethylbenzene (TMB) were added to the conventional SBA-15 synthesis solution to obtain platelet SBA-15 (SBA-15-p) materials with expanded pores. Based on the results of conventional characterization techniques and in situ small-angle X-ray scattering experiments, the key step to obtain a well-ordered 2D hexagonal pore structure without vesicle contamination was the pre-hydrolysis of tetraethyl orthosilicate (TEOS) in the Zr(IV) containing synthesis solution for about 25 min before adding TMB as the pore swelling agent.
Facile synthesis of platelet and short-channel SBA-15 (Zr-containing mesoporous silica materials)
Chem. Mater. 2004, 16, 21, 4174–4180
https://doi.org/10.1021/cm049247b
Facile synthesis of functional mesoporous materials with platelet morphology and short channels (CH3-, phenyl-, thiol- (SH-), sulfonic acid- (SO3H-), amine- (NH2-))
Chem. Mater. 2008, 20, 12, 3906–3916
https://doi.org/10.1021/cm703500c
Catalytic application of Zr-incorporated SBA-15 in pinacol-rearrangement (dehydration of diol compounds)
Journal of Catalysis 2010, 270, 196-205
https://doi.org/10.1016/j.jcat.2009.12.020
Tuning the pores of SBA-15 for enzyme adsorption
J. Mater. Chem. 2011, 21, 5693-5703
https://doi.org/10.1039/C0JM03591B